Our world as a simulated reality...
In The God Delusion, Richard Dawkins briefly mentions the interesting theory proposed by computer expert that our entire universe may actually be a computer simulation created by a more advanced civilization. Professor Dawkins stated, at the time of the last edition of The God Delusion, he had not thought of a way to successfully refute this idea. I concede that there is not way to actively disprove the idea of a simulated reality, but I think there may be at least one way to show that it is logically unlikely:
I think most of us would probably agree that if our race ever evolves to a point that is it able to create a simulated universe such as the one we live in, complete with our consciousness and emotions, it will be at least hundreds, perhaps thousands of years in the future. Therefore, any race that accomplished this feat would also likely have accomplished many other (slightly less miraculous) pieces of advanced technology in the meantime. Flying cars, advanced quantum computers, and somewhat advanced "thinking robots" would logically come before such a simulated reality. So, why would the computer programmers of our universe have left all this technology out of our world? Why do we also not have readily available flying cars and robotic butlers?? The fact that our designers left out hundreds or thousands of years of technology in our simulated world would be the logical equivalent of humans today creating a simulated world that had only the technology of the Stone Age.
While not impossible, I think this makes this hypothesis logically weak. It is much more logical that the reason we do not posses these advanced technologies do not exist in our world, is because they do not exist in any world (at least not any world that would have created us).